Floated singulation

ABSTRACT

A microelectronic device has a substrate attached to a substrate pad on a first face of the substrate, and a component attached to the substrate on the first face. The substrate has a component placement guide on the first face. The substrate has a singulation guide on a second face of the substrate, located opposite from the first face. The microelectronic device is formed by attaching the component to a substrate sheet which contains the substrate. The substrate sheet with the component is mounted on a singulation film so that the component contacts the singulation film. The singulation guide on the second face of the substrate is located opposite from the singulation film. The substrate is singulated from the substrate sheet. The substrate with the component is attached to the substrate pad on the first face of the substrate, adjacent to the component.

FIELD

This disclosure relates to the field of microelectronic devices. Moreparticularly, this disclosure relates to singulation of substrates inmicroelectronic devices.

BACKGROUND

A microelectronic device may have a substrate attached to substratepads, such as pads of a lead frame, on one face of the substrate. Themicroelectronic device may further have a component attached to thesubstrate on the same face of the substrate. Assembling themicroelectronic device presents challenges. If the component is attachedto the substrate before the substrate is attached to the substrate pads,the substrate must be singulated, and the component attached usingexpensive fixtures and complicated assembly processes. If the componentis attached to the substrate after the substrate is attached to thesubstrate pads, the lead frame must be flipped to accommodate placingthe component on the substrate. Both approaches incur undesirablefabrication costs and complexities.

SUMMARY

The present disclosure introduces a microelectronic device having asubstrate attached to a substrate pad on a first face of the substrate.The substrate has a component placement guide which is detectable at thefirst face. A component is attached to the substrate on the first faceof the substrate. The substrate has a singulation guide which isdetectable at a second face of the substrate, located opposite from thefirst face.

The microelectronic device is formed by attaching the component to asubstrate sheet which contains the substrate. The substrate sheet withthe component is mounted on a singulation film so that the componentcontacts the singulation film, and the singulation guide on thesubstrate is located opposite from the singulation film. The substrateis singulated from the substrate sheet. The substrate with the componentis attached to the substrate pad on the first face.

BRIEF DESCRIPTION OF THE VIEWS OF THE DRAWINGS

FIG. 1A through FIG. 1H are perspective views, cross sections, and topviews of a microelectronic device having a substrate attached tosubstrate pads and a first component attached to the substrate on thesame face, depicted in stages of an example method of formation.

FIG. 2A through FIG. 2F are perspective views, cross sections, and topviews of a microelectronic device having a substrate attached tosubstrate pads and a first component attached to the substrate on thesame face, depicted in stages of an example method of formation.

DETAILED DESCRIPTION

The present disclosure is described with reference to the attachedfigures. The figures are not drawn to scale and they are provided merelyto illustrate the disclosure. Several aspects of the disclosure aredescribed below with reference to example applications for illustration.It should be understood that numerous specific details, relationships,and methods are set forth to provide an understanding of the disclosure.The present disclosure is not limited by the illustrated ordering ofacts or events, as some acts may occur in different orders and/orconcurrently with other acts or events. Furthermore, not all illustratedacts or events are required to implement a methodology in accordancewith the present disclosure.

A microelectronic device includes a substrate attached to one or moresubstrate pads on a first face of the substrate. The substrate has acomponent placement guide which is detectable at the first face. Thecomponent placement guide may be detectable by visual inspection,optionally using a microscope, a camera, or another detection apparatus.The microelectronic device includes a first component attached to thesubstrate on the first face of the substrate. The substrate has asingulation guide which is detectable at a second face of the substrate,located opposite from the first face. The singulation guide may bedetectable by visual inspection, a camera, or another detectionapparatus. The microelectronic device may optionally include a secondcomponent attached to the second face of the substrate.

The microelectronic device is formed by attaching the component to asubstrate sheet which contains the substrate. The substrate sheet maycontain additional substrates, and additional components may be attachedto the additional substrates. The substrate sheet with the component ismounted on a singulation film so that the component contacts thesingulation film. The singulation guide on the substrate is locatedopposite from the singulation film. The substrate is singulated from thesubstrate sheet. The substrate with the component is attached to thesubstrate pad on the first face.

FIG. 1A through FIG. 1H are perspective views, cross sections, and topviews of a microelectronic device having a substrate attached tosubstrate pads and a first component attached to the substrate on thesame face, depicted in stages of an example method of formation.Referring to FIG. 1A, this example method of formation of themicroelectronic device 100 starts with acquiring a substrate sheet 102.The substrate sheet 102 includes a substrate 104 of the microelectronicdevice 100. The substrate 104 may include electrical conductors 106separated by one or more electrically non-conductive materials 108. Theelectrical conductors 106 may include, for example, copper traces, thickfilm conductors, aluminum interconnects, or wires. The one or moreelectrically non-conductive materials 108 may include, for example,layers of polymer, such as epoxy or polyester, optionally reinforcedwith fiberglass. The electrical conductors 106 may provide passivecomponents such as a winding of an inductor, windings of a transformer,a resistor, or plates of a capacitor, or may provide electricalconnections between components that are subsequently attached to thesubstrate 104.

The substrate 104 has a first face 110 and a second face 112 locatedopposite from, and parallel to, the first face 110. The substrate sheet102 extends past the substrate 104 in at least one lateral direction,and may extend past the substrate 104 in all lateral directions, asindicated in FIG. 1A. The term “lateral” is used in this example todenote directions parallel to the first face 110 and the second face112. A thickness of the substrate 104, that is, a distance between thefirst face 110 and the second face 112, may be, for example, 0.1millimeters to 2 millimeters. Lateral dimensions of the substrate 104may be, for example, 3 millimeters to 30 millimeters. The substratesheet 102 may include additional substrates, not shown in FIG. 1A, foradditional microelectronic devices, not shown in FIG. 1A. The substrate104 may optionally include bond pads 114 at the second face 112.

The substrate 104 includes a component placement guide 116 which isdetectable at the first face 110. The component placement guide 116includes one or more features that provide an indication of a desiredlocation for subsequently attaching a first component 128, shown in FIG.1B, to the substrate 104 on the first face 110. The component placementguide 116 may be detectable by visual inspection, optionally using amicroscope, a camera, or another detection apparatus. The componentplacement guide 116 may have, for example, a rectangle surrounding anarea for the desired location, corner fiducials, such as crosses, atcorners of the area for the desired location, or lines parallel tolateral edges of the area for the desired location. In this example, thesubstrate sheet 102 includes a first solder mask 118 at the first face110. The first solder mask 118 is patterned to provide the componentplacement guide 116, which may be implemented as a rectangle surroundingthe area for the desired location, as depicted in FIG. 1A. The componentplacement guide 116 may be visible to a camera of a pick and place tool,enabling automated placement of the first component 128 on the area forthe desired location. Other implementations of the component placementguide 116 are within the scope of this example.

The substrate 104 includes a singulation guide 120 which is detectableat the second face 112. The singulation guide 120 includes features thatprovide an indication of desired paths for subsequently singulating thesubstrate 104 from the substrate sheet 102. The singulation guide 120may be detectable by visual inspection, optionally using a microscope, acamera, or another detection apparatus. In this example, the substratesheet 102 includes a second solder mask 122 at the second face 112. Thesecond solder mask 122 is patterned to provide the singulation guide120, which may be implemented as open paths, free of the second soldermask 122. The singulation guide 120 is visible to a camera of asingulation tool, such as a saw tool, enabling automated singulation ofthe substrate 104 from the substrate sheet 102. The second solder mask122 may be patterned to have bond pad openings 124 which expose the bondpads 114 at the second face 112, if present. Other implementations ofthe singulation guide 120 are within the scope of this example.

In one version of this example, the first solder mask 118 and the secondsolder mask 122 may be patterned using a same photolithography mask,advantageously reducing a fabrication cost of the microelectronic device100. Using the same photolithography mask to pattern the first soldermask 118 and the second solder mask 122 may result in the componentplacement guide 116 being implemented as a rectangle extending todesired paths for subsequently singulating the substrate 104, asdepicted in FIG. 1A. Using the same photolithography mask to pattern thefirst solder mask 118 and the second solder mask 122 may result in dummyopenings 126 in the first solder mask 118, corresponding to the bond padopenings 124 in the second solder mask 122; the dummy openings 126 donot expose any bond pads at the first face 110.

Referring to FIG. 1B, a first component 128 is attached to the substrate104 on the first face 110. In versions of this example in which thesubstrate 104 includes a winding of an inductor or windings of atransformer, the first component 128 may be implemented as a slab of amagnetic material having a relative magnetic permeability greater than1, to improve a quality factor, sometimes referred to as a Q-factor, ofthe inductor, or to improve a power transfer efficiency of thetransformer. The first component 128 may include, for example, iron,nickel, or cobalt. In other versions of this example, the firstcomponent 128 may include one or more passive components such as aresistor, an inductor, or a capacitor. In further versions of thisexample, the first component 128 may include one or more activecomponents such as a transistor, a diode, or an integrated circuit.

The first component 128 may be attached to the substrate 104 by anadhesive 130, as depicted in FIG. 1B. Alternatively, the first component128 may be attached to the substrate 104 by solder, tape, or mechanicalfasteners, for example. The first component 128 may have lateral edgesaligned with the component placement guide 116.

Referring to FIG. 1C, the substrate sheet 102 and the first component128 are mounted on a singulation film 132, so that the first component128 contacts the singulation film 132. The singulation film 132 may beimplemented as a saw film, for example. The substrate sheet 102 may beoffset from the singulation film 132 by the first component 128, so thatthe substrate sheet 102 does not directly contact the singulation film132, as depicted in FIG. 1C. The singulation film 132 may be held by asingulation frame, not shown in FIG. 1C, around a lateral perimeter ofthe singulation film 132.

Referring to FIG. 1D, the substrate 104 is singulated from the substratesheet 102 by a singulation process. The singulation process may beimplemented as a saw process using a saw blade 134, as depicted in FIG.1D. In versions of this example in which the singulation process isimplemented as the saw process, the saw process may be performed so thatthe saw blade 134 does not cut into the singulation film 132 under thesubstrate 104, which may prolong a working life of the saw blade 134,advantageously reducing the fabrication cost of the microelectronicdevice 100. The substrate 104 may be singulated from the substrate sheet102 along the singulation guide 120, as indicated in FIG. 1D. Othersingulation methods, such as laser ablation, are within the scope ofthis example.

Referring to FIG. 1E, the substrate 104 is removed from the singulationfilm 132 of FIG. 1D and is attached to substrate pads 136 of themicroelectronic device 100. The substrate 104 is attached to thesubstrate pads 136 at the first face 110 of the substrate 104 at one ormore locations adjacent to the first component 128. The substrate pads136 may be implemented as parts of a lead frame 138, for example. Thesubstrate 104 may be attached to substrate pads 136 using a firstadhesive 140, as indicated in FIG. 1E. Other methods for attaching thesubstrate 104 to the substrate pads 136, such as soldering, taping, orwelding, are within the scope of this example. Attaching the substrate104 to the substrate pads 136 at the first face 110 may enabletransferring the substrate 104 and the first component 128 from thesingulation film 132 to the substrate pads 136 while maintaining aconstant orientation of the first component 128 relative to thesubstrate 104, that is, maintaining the first component 128 below thesubstrate 104. Maintaining the constant orientation of the firstcomponent 128 relative to the substrate 104 may be performed by a toolwhich is configured to maintain the constant orientation during thetransfer process. Conventional fabrication flows mount the substratesheet 102 on the singulation film 132 with the substrate sheet 102directly contacting the singulation film 132, necessitating a reversalof the orientation of the first component 128 relative to the substrate104 during the transfer process, which requires a more expensive toolcapable of reversing the orientation during the transfer, sometimesreferred to as a flip-chip die bonder, compared to the tool configuredto maintain the constant orientation during the transfer process. Thus,maintaining the constant orientation of the first component 128 relativeto the substrate 104 during the transfer from the singulation film 132to the substrate pads 136 may enable reduced fabrication cost for themicroelectronic device 100.

FIG. 1F is a top view of the microelectronic device 100. The lead frame138 may include a first die pad 142 and a second die pad 144, optionallyconnected to the substrate pads 136 by portions of the lead frame 138. Afirst die 146 may be attached to the first die pad 142, and a second die148 may be attached to the second die pad 144. The first die 146 mayhave first die bond pads 150, and the second die 148 may have second diebond pads 152. The first die 146 and the second die 148 may beimplemented as integrated circuits, discrete semiconductor devices, orsuch.

Referring to FIG. 1G, wire bonds 154 are formed to electrically couplethe first die 146 to the substrate 104, and to couple the second die 148to the substrate 104. The wire bonds 154 may also electrically couplethe first die 146 and the second die 148 to external leads 160, shown inFIG. 1H, of the microelectronic device 100. The wire bonds 154 mayterminate on the bond pads 114 of the substrate 104, the first die bondpads 150, and the second die bond pads 152, as depicted in FIG. 1G.

A second component 156 may optionally be attached to the substrate 104on the second face 112. The second component 156 may be attached using asecond adhesive 158, or by a solder, a tape, or by microwelds. Inversions of this example in which the substrate 104 includes a windingof an inductor or windings of a transformer, the second component 156may be implemented as a slab of a magnetic material having a relativemagnetic permeability greater than 1, similar to the first component128, to further improve the quality factor of the inductor, or toimprove the power transfer efficiency of the transformer. In otherversions of this example, the second component 156 may include one ormore passive components such as a resistor, an inductor, or a capacitor.In further versions of this example, the second component 156 mayinclude one or more active components such as a transistor, a diode, oran integrated circuit.

FIG. 1H is a cross section of the completed microelectronic device 100through the substrate 104. The microelectronic device 100 includes theexternal leads 160, which may be parts of the lead frame 138. One ormore of the wire bonds 154 may connect to one or more of the externalleads 160. A package structure 162 is formed on the substrate 104, thefirst component 128, and the second component 156. The package structure162 may include a polymer material, such as epoxy, formed by a moldingprocess. The package structure 162 may extend partway onto the externalleads 160, as depicted in FIG. 1H.

FIG. 2A through FIG. 2F are perspective views, cross sections, and topviews of a microelectronic device having a substrate attached tosubstrate pads and a first component attached to the substrate on thesame face, depicted in stages of an example method of formation.Referring to FIG. 2A, this example method of formation of themicroelectronic device 200 starts with acquiring a substrate sheet 202.The substrate sheet 202 includes a substrate 204 of the microelectronicdevice 200. The substrate 204 may include electrical conductors 206separated by one or more electrically non-conductive materials 208. Theelectrical conductors 206 may provide electrical connections betweencomponents that are subsequently attached to the substrate 204, or mayprovide passive components such as a winding of an inductor, windings ofa transformer, a resistor, or plates of a capacitor.

The substrate 204 has a first face 210 and a second face 212 locatedopposite from, and parallel to, the first face 210. The substrate sheet202 extends past the substrate 204 in at least one lateral direction,and may extend past the substrate 204 in all lateral directions. Theterm “lateral” is used in this example to denote directions parallel tothe first face 210 and the second face 212. The substrate sheet 202 mayinclude additional substrates, not shown in FIG. 2A, for additionalmicroelectronic devices, not shown in FIG. 2A.

The substrate 204 includes a component placement guide 216 which isdetectable at the first face 210. The component placement guide 216includes one or more features that provide an indication of a desiredlocation for subsequently attaching a first component 228, shown in FIG.2B, to the substrate 204 on the first face 210. The component placementguide 216 may be detectable by visual inspection, a camera, or anotherdetection apparatus. The component placement guide 216 may have, forexample, lines parallel to lateral edges of the area for the desiredlocation, a rectangle surrounding an area for the desired location, orcorner fiducials, such as crosses, at corners of the area for thedesired location. In this example, the substrate 204 may have a portionof the electrical conductors 206 extending to the first face 210, orproximate to the first face 210, to provide the component placementguide 216. The component placement guide 216 may be covered by amaterial layer, not shown in FIG. 2A, through which the componentplacement guide 216 can still be detected, such as a transparent layerof dielectric material. The component placement guide 216 is visible toa camera of a pick and place tool, enabling automated placement of thefirst component 228 on the area for the desired location. Otherimplementations of the component placement guide 216 are within thescope of this example.

In this example, the substrate 204 may further include firstinput/output (I/O) pads 264 extending to the first face 210. The firstI/O pads 264 may include, for example, copper, nickel, palladium, gold,or platinum. The first I/O pads 264 may be electrically connected to theelectrical conductors 206.

In this example, the substrate sheet 202 includes a solder mask 222 atthe second face 212. The substrate 204 includes a singulation guide 220at the second face 212, implemented as open paths in the solder mask222. The singulation guide 220 includes features that provide anindication of desired paths for subsequently singulating the substrate204 from the substrate sheet 202. The singulation guide 220 may bedetectable by visual inspection, a camera, or another detectionapparatus. The singulation guide 220 may be visible to a camera of asingulation tool, such as a saw tool, enabling automated singulation ofthe substrate 204 from the substrate sheet 202. Other implementations ofthe singulation guide 220 are within the scope of this example.

The solder mask 222 may have bond pad openings 224 which expose bondpads 214 at the second face 212. The bond pads 214 may include, forexample, aluminum, copper, nickel, palladium, gold, or platinum. Thebond pads 214 may be electrically connected to the electrical conductors206. The solder mask 222 may have solder pad openings 266 which exposesecond I/O pads 268 at the second face 212. The second I/O pads 268 mayinclude, for example, copper, nickel, palladium, gold, or platinum. Thesecond I/O pads 268 may be electrically connected to the electricalconductors 206. For the purposes of this disclosure, the second face 212includes external surfaces of the second I/O pads 268.

Referring to FIG. 2B, a first component 228 is attached to the substrate204 on the first face 210. In this example, the first component 228 mayinclude one or more active components such as a transistor, a diode, oran integrated circuit. Further, the first component 228 may include oneor more passive components such as a resistor, an inductor, or acapacitor. In this example, the first component 228 may be implementedas an integrated circuit, a discrete semiconductor device, amicroelectrical mechanical system (MEMS) device, an electro-opticaldevice, or a microfluidics device, for example. In this example, thefirst component 228 may be attached to the substrate 204 by a solderprocess which forms solder connections 270 on the first I/O pads 264.The first component 228 may optionally be offset from the substrate 204by the solder connections 270, nevertheless, for the purposes of thisdisclosure, the first component 228 is attached to the substrate 204 onthe first face 210. Other methods for attaching the first component 228are within the scope of this example, such as using an electricallyconductive adhesive to form electrical connections on the first I/O pads264.

Referring to FIG. 2C, a second component 256 is attached to thesubstrate 204 n the second face 212. FIG. 2C shows the substrate 204above the first component 228, which is a vertically reversedorientation from FIG. 2B. In this example, the second component 256 mayinclude one or more active components, and may further include one ormore passive components. The second component 256 may be implemented asan integrated circuit, a discrete semiconductor device, a MEMS device,an electro-optical device, or a microfluidics device, for example. Thesecond component 256 may be implemented as a different device type thanthe first component 228. The second component 256 may be attached to thesubstrate 204 by an adhesive process using an electrically conductiveadhesive, which forms electrical connections 272 on the second I/O pads268. The second component 256 may optionally be offset from thesubstrate 204 by the electrical connections 272, nevertheless, for thepurposes of this disclosure, the second component 256 is attached to thesubstrate 204 on the second face 212.

Referring to FIG. 2D, the substrate sheet 202, the first component 228,and the second component 256 are mounted on a singulation film 232, sothat the first component 228 contacts the singulation film 232. Thesubstrate sheet 202 may be offset from the singulation film 232 by thefirst component 228, so that the substrate sheet 202 does not directlycontact the singulation film 232, as depicted in FIG. 2D. The substrate204 is singulated from the substrate sheet 202 by a singulation process,such as a saw process using a saw blade 234, as depicted in FIG. 2D. Thesubstrate 204 may be singulated from the substrate sheet 202 along thesingulation guide 220, as indicated in FIG. 2D. Other singulationmethods, such as laser ablation, are within the scope of this example.

Referring to FIG. 2E, the substrate 204 is removed from the singulationfilm 232 of FIG. 2D and is attached to substrate pads 236 of themicroelectronic device 200. The substrate pads 236 may be implemented asparts of a lead frame 238 having external leads 260, for example. Thesubstrate 204 is attached to the substrate pads 236 at the first face210 of the substrate 204 at one or more locations adjacent to the firstcomponent 228. The substrate 204 may be attached to substrate pads 236using an adhesive 240. Other methods for attaching the substrate 204 tothe substrate pads 236, such as soldering, taping, or welding, arewithin the scope of this example. Attaching the substrate 204 to thesubstrate pads 236 at the first face 210 may enable transferring thesubstrate 204 and the first component 228 from the singulation film 232to the substrate pads 236 while maintaining a constant orientation ofthe first component 228 relative to the substrate 204, accruing theadvantage described in reference to FIG. 1E.

Referring to FIG. 2F, wire bonds 254 are formed to make electricalconnections to the substrate 204. The wire bonds 254 may electricallycouple the substrate 204 to the external leads 260, for example. Thewire bonds 254 may terminate on the bond pads 214 of the substrate 204,as depicted in FIG. 2F. Formation of the microelectronic device 200 maybe continued by forming a package structure 262 that contains thesubstrate 204, the first component 228, and the second component 256.The external leads 260 may be shaped to provide a dual-flat no-leads(DFN) configuration or a quad-flat no-leads (QFN) configuration.

While various embodiments of the present disclosure have been describedabove, it should be understood that they have been presented by way ofexample only and not limitation. Numerous changes to the disclosedembodiments can be made in accordance with the disclosure herein withoutdeparting from the spirit or scope of the disclosure. Thus, the breadthand scope of the present invention should not be limited by any of theabove described embodiments. Rather, the scope of the disclosure shouldbe defined in accordance with the following claims and theirequivalents.

What is claimed is:
 1. A microelectronic device, comprising: a substratehaving a first face and a second face, wherein the second face islocated opposite from the first face, the substrate having a componentplacement guide which is detectable at the first face, and a singulationguide which is detectable at the second face; a first component attachedto the substrate on the first face; and a first substrate pad, whereinsubstrate is attached to first substrate pad on the first face.
 2. Themicroelectronic device of claim 1, further including a second substratepad, wherein the substrate is attached to the second substrate pad onthe first face.
 3. The microelectronic device of claim 1, wherein: thesubstrate includes windings of a transformer; and the first componentincludes a slab of a magnetic material having a relative magneticpermeability greater than
 1. 4. The microelectronic device of claim 1,further including a second component attached to the second face.
 5. Themicroelectronic device of claim 1, wherein the singulation guideincludes open paths in a solder mask.
 6. The microelectronic device ofclaim 1, wherein the component placement guide includes a rectangle in asolder mask.
 7. The microelectronic device of claim 1, wherein thecomponent placement guide includes electrical conductors in thesubstrate.
 8. The microelectronic device of claim 1, further including adie attached to a die pad of the microelectronic device, the die beingelectrically coupled to the substrate, wherein the die is selected fromthe group consisting of an integrated circuit, a discrete semiconductordevice, a microelectrical mechanical system (MEMS) device, anelectro-optical device, and a microfluidics device.
 9. A method offorming a microelectronic device, comprising: acquiring a substratesheet which includes a substrate, the substrate having a first face anda second face, wherein the second face is located opposite from thefirst face, the substrate having a component placement guide which isdetectable at the first face, and a singulation guide which isdetectable at the second face; attaching a first component to thesubstrate on the first face; mounting the substrate sheet on asingulation film, wherein the first component contacts the singulationfilm, and the singulation guide is located opposite from the singulationfilm; singulating the substrate from the substrate sheet; removing thesubstrate and the first component from the singulation film; andattaching the substrate to a first substrate pad of the microelectronicdevice, wherein the substrate is attached to the first substrate pad onthe first face.
 10. The method of claim 9, wherein the singulation guideincludes open paths in a solder mask.
 11. The method of claim 9, whereinthe component placement guide includes a rectangle in a solder mask atthe second face.
 12. The method of claim 9, wherein the componentplacement guide includes electrical conductors in the substrate.
 13. Themethod of claim 9, further including attaching the substrate to a secondsubstrate pad, concurrently with attaching the substrate to the firstsubstrate pad, wherein the substrate is attached to the second substratepad on the first face.
 14. The method of claim 9, further includingattaching a second component to the substrate on the second face beforethe substrate is singulated from the substrate sheet.
 15. The method ofclaim 9, further including attaching a second component to the substrateon the second face after the substrate is singulated from the substratesheet.
 16. The method of claim 9, wherein the singulation film does notcontact the substrate sheet.
 17. The method of claim 9, whereinsingulating the substrate is performed by a saw process, and a saw bladeused in singulating the substrate does not contact the singulation film.18. The method of claim 9, wherein attaching the first component to thesubstrate is performed using an adhesive.
 19. The method of claim 9,wherein attaching the substrate to the first substrate pad is performedusing an adhesive.
 20. The method of claim 9, further includingattaching a die to a die pad and forming an electrical connectionbetween the die and the substrate.